How can I complaint against slow speed provided by my isp

I subscribed to gtpl 5500 rupees plan for 40mbps for 1 year but, I only get 300kBps(Bytes) on all servers except google servers. I just feels like there is artificial cap set at that speed upload speed still remain close to 18 mbps on all the servers I have complained many time now I am fed up and just want my money back. How can a complaint the customer care is just unhelpful

Easiest way to provide subpar services to customer is to lock them for long term plans.
Try to contact the lco/ local technician guy if you have his number .